There was a bloke who burnt a house down on the old firm I worked for, before I started there. Soldering in loft and things got out of hand, apparently the roof tiles were popping off like fireworks, whole house burnt down because it was in a really awkward spot for the fire engine to get too!
When I was a 1st year apprentice my boss asked me to put the blow lamp onto an elbow on the outisde of the house, while he twisted it straight with a pair of grips, so off I go. Turns out it was a gas pipe and the gas was still on, he twisted it and it came out the fitting! all I saw was a fire ball go over my head, i'm running around like :willy_nilly:and my boss comes out puts a claw hammer through the customers meter box and turns gas off! Lucky it didn't burn back really.
I've put core drills through ring mains a few times, normally when they run the cables in the 150mm 'safe zone' in the corners, pity they don't feckin tell anyone about them! (only found out when i did 17th)
I forgot to cap off the return from a coil once when doing a standard to combi, filled up and was wondering why it was taking so long, took me a few minutes then I remembered. ran upstairs and lifted the floorboard to find about 2 inches of water sitting on this ceiling, how it stayed up i'll never know!
Ran down and put a hole in the ceiling in a few places and it was gushing out, filled one of those big gorilla tubs up. Went back a few days later and painted the ceiling and everything was fine!
I mate put a 16mm flat bit in the end of a makita cordless through a lead sheathed incoming electric main in an old cottage which was semi buried in the wall and really hard to spot, looked like he'd seen a ghost. The worse thing was they had daisy chained the main into next door as well so both houses lost power and the electric board had to cut and resin block the main live which cost the company a fair few quid!